Make-and-break device



June 1929- E. c. FICHTNER ETAL 1,716,119

MAKE AND BREAK DEVICE,

Filed Aug. 27. 1926 INVENTURS EDWIN C'.FJCHTHIR JoSEPH ll, .S'IMaIY /l TTORNEY Patented June 4, 1929.

UNITED STATES PATENT OFFICE.

EDWIN C. FICHTNER, OF SAN FRANCISCO, AND JOSEPH H. SIMON, OF OAKLAND, CALI- FORNIA. I

MAKE-AND-BREAK DEVICE.

Application filed August 27, 1926. SeriaI No. 131,863.

The present invention is an improved snap switch or make and break mechanism. The invention relates to means, associated with a movable member, such as a bimetallic thermostatie arm, for opening and closing a circuit, automatically, in response to fluctuation of heat generated by an electrical element served by said circuit.

The objects of our invention include (1). The provision of a device of the character described in which a snap action is employed which will be very fast in its movement and which will have a greater distance of travel than that of the thermostatic member by which it is actuated without impeding, to any appreciable degree, the movement of said member.

(2). Our invention contemplates a spring bow said how may be flexed to either an extreme concave or convex position with respect to its mounting, and which can repose only in one of said extreme positions. The resilient how when urged in either direction by the movement of said thermostatic member will snap to its repose position, making or breaking a circuit by a contact carried on said how, which serves as a bridge between contacts carried by said member.

In this specification and the annexed drawings, the invention is illustrated in the form considered to be the best, but it is not limited to such form because it may be embodied in other forms, and it is also to be understood that in and by the claim following description it is desired to cover the invention in whatever form it may be embodied.

In the accompanying drawings Figure 1 is an end view of a bimetallic arm and a side view of our device as it would appear in a closed circuit position. v

Figure 2 is a side elevation of Figure 1, and

Figures 3 and 4 are views corresponding to Figures 1 and 2, respectively, showing the parts as they would appear in the open circuit position.

Referring to the drawings the numeral 1 indicates a bimetallic arm of a well known 60 metal adapted to warp in response to the action of heat because of the difference in the coetficient of expansion of the laminated members of the strip of which said arm is formed. Arm 1 is secured at one end, as by mounted in yieldable bearings whereby.

a screw 2, to a fixed member 3. The end of arm 1 remote from its base 3 is free to flex to the position shown in Figure 4. Secured 1n anywell' known manner to the free end of arm 1 are contacts 4 and 6 to which are attached wires A and B which are service Wires of a circuit in which ment indicated symbolically at 7. The arm 1 is provided with a finger 8 which is secured in rigid relation thereto. At 9 is shown a base which may or may not be integral with base 3. To base 9 is secured, as by screw 11, a bow 12 of flexible resilient material.

7 The ends of bow 12 are bent inwardly as indicated at 12 to engage and retain a strip 13 of flat spring steel. The length of the strip 13 is greater than the chord between the bearings 12 with the result that said strip is always in repose in one or the other of the positions shown in Figures 1 and 3. Our device is so assembled that the strip 13 is between the arm 1 and finger 8 in transverse relation thereto, so that, as said arm is reciprocated, the arm 1 will in one direction and the finger 8 inthe opposite direction. The strip 13 carries near the center thereof a silver contact 14 mounted in floating relation thereto so that it' will adjust itself flatly against the contacts 4-6.

Assuming that our device is installed on a cricuit governing an electric cooking utensil, the parts, when cold, are in the position shown in Figures 1 and 2. Current passes through which are bridged and closed by contact 14. When temperature rises to a point sufficient to flex arm 1 to the position showninFigures3 and 4 the downward movement of arm 1 forces strip 13 to a point where it passes the central line of its bearings (indicated at Figures 1 and 3 at C-C) whereupon said spring snaps to its repose position shown in Fig. 3 breaking contact between terminals 4 and 6, thus opening the circuit.

Conversely, when the temperature subsides to a degree where arm 1 will be restored to its normal position (Fig. 2) the finger 8, attached to said arm, bears upward on the under side of spring strip 13 until said, spring strip passes the central line CG, whereupon said strip snaps to the position shown in Figure 1, contact 14 bridging contacts 46 and closing the circuit. The member 12 of resilient material flexes when the strip 13 nears its move said strip I wires A-B, and contacts 4 and 6,v

isa heating elecentral plosition (CC) and thereafter assists in t e snap action of said member.

Attention is particularly direction to the action of the switch, and especially the bowed supporting member 12. It is evident that if the flexible contact member 13 is mounted between rigid supports, that the spring member will require gradually increasing force to flex it as it reaches the central plane of its travel, and that it will also be necessary to distort the, spring in order to permit it to pass the central plane-of its travel; thus increased pressuremust be exerted as the contact member moves to its center point. In other devices of switches having yieldable end bearings the forces exerted have the same result, and it has. been one of the principal features of the present invention to provide the bowed support 12 which will progressive ly adjust itself to the flexing movement of the contact member 13 and will insure that the contact member may be moved by a substantially constant pressure at all times. This makes the device operate in a more accurate manner, and makes it possible to adjust the parts to operate with nicety.

Obviously the contacts 4 and 6 might be made stationary and the support 12 be reciprocated by any means and the same results accomplished. It will thus be seen that the structure here disclosed is quite simple as to material and manufacturing costs, and

that it may be constantly operated without danger of getting "out of order.

While we have shown the preferred form of our invention, it is to be understood that various changes may be made in the process without departing from the invention as defined in the appended claim.

We claim 7 An electric thermal switch comprising a bimetallic thermally responsive element adapted to flex under changes of temperature, a pair of contacts carried by said bimetallic element, a snap action mechanism adapted to cooperate with said bimetallic 'elementto produce a quick make and break in a circuit controlled thereby comprising a bowed spring member extending at right angles to the bimetallic element and mounted in a yielding support, a bridging contact, mounted upon said bowed spring member adapted to bridge the contacts carried by said bimetallic element, and means projecting from said bimetallic element adapted to cooperate with the contacts carried thereby to cause said bridging contact to snap. therebetween as the bimetallic thermal element is flexed under the influence of temperature changes.

In-testimony whereof we aflix our signatures.

EDWIN .0. FICHTNER. JOSEPH H. SIMON. 

